Fig. 1.

Computed trap models with various strain distributions and layer setups without prestress. (A) Measured strain distributions and various load cases for simulations with transformation of coordinate systems. Relationships between opening angle and maximum absolute strain (B) for measured strain distributions and (C) for interpolated strain distributions in all layer setups. The abbreviations correspond to the number of tissue layers (three or two), the behavior of these layers during closure (expansion, +; contraction, −; no actuation, 0), and the extent of expansion or contraction (in %). Moreover, the relative thicknesses of the tissue layers are depicted (see SI Appendix for more details). The only models performing snap-through are the bilayered 2+−100 (inner epidermis contracts as much as the outer epidermis expands) measured load case (B1) and interpolated load case (C1), which, however, do not fit the observed geometrical behavior of the real trap (Movies S7 and S8). Details for all models can be extracted from SI Appendix, Fig. S2.